1. Field of the Invention
This invention relates to an upsetter for upsetting end portions of elongated materials of, for example, steel and like material, and more particularly to improvements in clamp dies for upsetters with a horizontal die arrangement.
2. Description of the Prior Art
Upsetters basically consist of a grip mechanism which holds one end of a workpiece against slipping deviations when subjected to a thust in the upsetting stage, by gripping the workpiece by part of a pair of radially split dies the other part of which define the outer shape of the product when closed, and an upsetting mechanism which upsets the workpiece by means of an axially reciprocable upsetting die. The upsetting machines are largely classified into two types depending upon the direction in which the dies are split.
The first is a vertical type which, as shown in FIGS. 1 and 2, has vertically split dies 1 and 2 which are opened and closed in the horizontal direction by a drive mechanism 8 provided on one side of the dies. The vertical upsetter has a U-shaped frame 3 which is open on the upper side and supports the aforementioned dies 1 and 2 on the inner side. In order to prevent the frame 3 from being expanded on the upper open side at the time of gripping a work member 4, a cross tie rod 5 is provided perpendicularly along the upper open side of the frame 3.
Therefore, in the vertical type upsetter with the dies 1 and 2 enclosed on four sides as seen in the direction of arrow II of FIG. 2, there invariably arises the necessity for moving work members 4 over a large distance on the front side of the machine when feeding and extracting them before and after the upsetting operation.
More specifically, as seen in FIGS. 1 and 2, a blank tube 4 which has its end portion heated in a furnace 7 is transferred laterally over a certain distance for delivery to the working position of the upsetter as indicated by arrow I and then moved in the longitudinal direction for insertion into the upsetter as indicated by arrow II. Work member 4 which has been gripped in the upsetter is then lowered stepwise as indicated by arrow III to undergo the primary and secondary operations in the dies 1 and 2. Upon completion of upsetting operation, the work member 4 is drawn out of the upsetter by moving the same longitudinally backward over a substantial distance as indicated by arrow IV and then lifted to the initial level as indicated by arrow V, followed by a lateral movement over a large distance as indicated by arrow VI for transfer to the location of the next operation.
Consequently, the operation by a vertical upsetter entails transfer of the heated or upset work member 4 in the lateral direction as indicated by arrows I and VI within a short time period in addition to substantial longitudinal movements in the directions of arrows II and IV and the vertical movements in the directions of arrows III and V. Namely, it has a drawback in that it requires complicated and costly transfer or handling mechanisms for moving the work member in lateral, longitudinal and vertical directions. Besides, there has to be provided a long path of travel in total to cope with the large breadth of the upsetter with the side drive mechanism and the transfer of work in three directions, resulting in a prolonged period of time for one cycle of operation, lower productivity and high production cost.
Especially in the case of hot forging, the work members cool off during transfer, so that larger power and energy sources are required for the forming operation and the number of consecutive operations which are possible per single heating is limited. Consequently, due to the difficulty of completing the forming operation with only one heating stage, there arise the necessities of die replacement and reheating of the work before finishing the forming process.
As seen in FIG. 3 which diagrammatically illustrates a drive mechanism and a die assembly of another vertical type upsetter, the respective clamp dies which are operated by a clutch/brake mechanism 6 are not capable of clamping simultaneously a plurality of works which have large variations in outside diameter. More particularly, the movable dies 2 consist of an upset die section 2A and a clamp die section 2B, and similarly the stationary dies 1 consist of an upset die section 1A and a clamp die section 1B, arranged such that the movable dies 2 in the successive positions are actuated simultaneously and that work members are upset by driving an upset punch 10 through a clutch/brake mechanism 10A and a drive mechanism 10B including a crank 9. However, it has been difficult to improve the productivity since work members with large variations in outside diameter have to be worked one by one, coupled with the complicated path of travel.
These drawbacks will be understood by reference to FIG. 4, wherein indicated at reference number 11 is an upsetter, at 12 a skid feeder, at 13 a work lift and at 14 a work kicker. As illustrated in FIG. 4(a), a blank tube type work member 4 is delivered in front of the upsetter 11 as denoted by arrow I and then loaded into the machine as indicated by arrow II of FIG. 4(b), closing the movable die 2 toward the stationary die 1 to clamp the work member 4 therebetween as shown by the reference character A. In the next phase of operation, a punch is advanced as indicated by the reference character B to effect the forging at the preceding position. In the succeeding phases, the movable die 2 is opened as depicted in FIG. 4(c) and the work is shifted and positioned in the die at the second position shown in FIG. 4(d), forging the work member in a similar manner as illustrated in FIG. 4(e). Thereafter, the forged work member 4A is drawn out of the upsetter and lifted up for transfer to a next point of operation. Thus, each work member has to be moved along a complicated path of travel which requires a long time per cycle of operation, and it is difficult to clamp simultaneously a plurality of tubes with large variations in outside diameter since the clamp dies of the respective stages are operated integrally, unavoidably inviting a material drop in productivity.
Known also in the art is the so-called horizontal type upsetter which overcomes the problem of a long and complicated path of travel inherent in the vertical type upsetter described above. As illustrated in FIG. 5, the horizontal type upsetter is provided with dies 16 which are split horizontally. The dies are opened and closed vertically by a drive mechanism 17 which is mounted over the die assembly, so that the upsetter has a reduced width as compared with the vertical type.
As shown in FIG. 5, in the horizontal type upsetter, work members which are passed horizontally through part of die 16 are moved back and forth in the longitudinal direction to avoid interference of pull rods 18 which produce the gripping force of the dies 16. That is, the works which are fed into the machine in a slightly retracted position to be clear of the pull rod 18 are pushed in and then fed laterally to undergo sequentially the forging in the first and second dies. Upon finishing the forming operation, the work member are retracted again to avoid contact with the other pull rod 18 and moved laterally out of the machine for transfer to the location of the next operation.
The horizontal type upsetter which has a smaller width needs a shorter path of travel and thus contributes to shortening the cycle time of the forming operation and enhancing productivity as compared with the vertical type. Another advantage of the horizontal type upsetter resides in the fact that the transfer and handling mechanism can be simplifed to a significant degree as the main routes of transfer are all on the same horizontal plane. Further, in contrast to the vertical type which is closed on four sides, the horizontal type upsetter permits observation the conditions of the products from three sides when the dies are opened and accordingly it has an advantage that some suitable measures can be taken promptly to remove the cause of any defect as soon as a defective product comes out.
Although the path of work travel in the horizontal upsetter is two-dimensional, that is to say, in one horizontal plane, the works have to be moved longitudinally backward or to the left as seen in FIG. 5 to evade collision with the pull rods 18 which can move only a small distance in the longitudinal direction. Namely, there still remains the problem of utilizing a complicated transfer or feed mechanism in the known horizontal upsetter which does not permit linear transfer of the work members and products.
Further, the clamp dies in the successive positions are arranged to be operated integrally or jointly even in the horizontal type upsetter, so that they cannot clamp simultaneously a plurality of work members which have large variations in outside diameter, thus leaving the problem of low productivity unsolved.